In the lunette over the door is a glazed terracotta sculpture by Andrea della Robbia depicting the Madonna with Saints Stephen and John.

Internally, the church, built on a Latin cross ground plan, has a nave and two side aisles, all in Romanesque style and dating from the early 13th century.

It is faced, in the opposite aisle, by a great bronze candelabrum by Maso di Bartolomeo (1440), having an elongated vase-shape from which seven branches protrude.

Maso also executed the balcony of the inner west wall, which in addition is decorated with a fresco of the Assumption by David and Ridolfo del Ghirlandaio.

In the south arm of the transept is the Renaissance tabernacle by the Da Maiano brothers: the Madonna with Child terracotta (1480) is by the more famous Benedetto.

Next is the Assumption Chapel, which was frescoed in 1435-1436 by the so-called Master of Prato and by a young Paolo Uccello, who painted the Stories of the Virgin and St. Stephen, completed by Andrea di Giusto in the lower section.

They show a bizarre fantasy of enchanted figures caught in a wide range of brilliant colors, and surrounded by Brunelleschi-like architectures.

On the lower north wall are depicted the Obsequies of St. Stephen, in which Lippi portrayed Pope Pius II, set in a Palaeo-Christian basilica, as an imposing figure in scarlet costume.

On the opposite wall is Herod's Banquet, showing a large hall in which Salome is performing her ballet, and the handing over of the head of John the Baptist to Herodias.

The Cintola Chapel (Italian: Cappella del Sacro Cingolo) is located under the last arch of the north aisle, next to the counter-façade.